Hybrid electric and other fuel efficient vehicles are becoming increasingly popular. Plug-in hybrid electric vehicles and plug-in fully electric vehicles represent another category of vehicle that has less dependency on petroleum-based fuel. These vehicles are known as plug-in hybrid vehicles because their onboard energy storage systems (e.g., battery packs) are recharged by connecting (plugging in) the vehicle to an outlet, a charger or other voltage source, as well as from regenerative capture. In contrast to the conventional hybrid electric vehicles currently on the market, a plug-in hybrid vehicle can utilize its onboard energy storage system as the primary propulsion system for an extended range (up to 50 miles in some cases). After the onboard energy storage system has been depleted of its usable energy, an internal combustion engine (ICE) and/or a fuel cell in the plug-in hybrid vehicle is used as the primary propulsion system. Another type of plug-in hybrid vehicle (i.e., range extended electric vehicle) uses electricity as its sole propulsion system—an ICE or a fuel cell is used to recharge the onboard energy storage system as needed during operation. Although regenerative braking can be used to partially recharge the onboard energy storage system in these plug-in hybrid vehicles, recharging is typically performed by a charger that is connected to the local power grid architecture.
The number of plug-in vehicles currently in operation is rather low. However, it is reasonable to forecast that the number of plug-in vehicles on the road will steadily increase over time. Indeed, it is likely that in the future a large number of plug-in vehicles will need to be recharged at the same time or during the same extended period of time (e.g., overnight or during working hours). This will create high demands on power grid architectures, which deliver power across cities, counties, states, and countries. For example, overloading of a power grid architecture may occur when a large number of plug-in vehicles are concurrently plugged in for purposes of recharging. In practice, a power grid architecture cannot be expected to handle full power demand at all electrical outlets at any given time. Accordingly, when charging plug-in vehicles, it cannot be assumed that power from the respective power grid architecture will always be available (due to high power demands during certain hours of the day, the dependency on variable power sources such as wind generated energy and solar energy, and other practical factors).